Beef Research News
Brought to you by Kansas State University College of Veterinary Medicine - Farm Animal Section
KSU Bull Evaluation and Management Conference
You are invited to attend the Kansas State Bull Evaluation and Management conference on Friday January 11, 2008 in Manhattan, KS. This conference is exclusively about bulls. This conference will be a comprehensive continuing education symposium on the selection, management, health maintenance, biosecurity, and fertility of bulls. Internationally recognized experts will provide up-to-date information to optimize bull productivity, utilization, and semen evaluation. For more information and to register, direct your browser to: www.vet.ksu.edu/CE/Bull.htm
Fetal protection against BVD following vaccination
The objective of this research was to evaluate the efficacy of a commercially available killed bovine viral diarrhea virus (BVDV) vaccine to protect against fetal infection in pregnant cattle continually exposed to cattle persistently infected with the BVDV. 60 crossbred beef heifers and 4 cows persistently infected with BVDV were used for this study. Beef heifers were allocated to 2 groups. One group was vaccinated twice (21-day interval between the initial and booster vaccinations) with a commercially available vaccine against BVDV, and the other group served as nonvaccinated control cattle. Estrus was induced, and the heifers were bred. Pregnancy was confirmed by transrectal palpation. Four cows persistently infected with BVDV were housed with 30 pregnant heifers (15 each from the vaccinated and nonvaccinated groups) from day 52 to 150 of gestation. Fetuses were then harvested by cesarean section and tested for evidence of BVDV infection.
1 control heifer aborted after introduction of the persistently infected cows. Bovine viral diarrhea virus was isolated from 14 of 14 fetuses obtained via cesarean section from control heifers but from only 4 of 15 fetuses obtained via cesarean section from vaccinated heifers; these proportions differed significantly. Conclusions and Clinical Relevance—A commercially available multivalent vaccine containing an inactivated BVDV fraction significantly reduced the risk of fetal infection with BVDV in heifers continually exposed to cattle persistently infected with BVDV. However, not all vaccinated cattle were protected, which emphasizes the need for biosecurity measures and elimination of cattle persistently infected with BVDV in addition to vaccination within a herd.
Grooms, D.L. S.R. Bolin, P.H. Coe, R.J. Borges, C.E. Coutu, Fetal protection against continual exposure to bovine viral diarrhea virus following administration of a vaccine containing an inactivated bovine viral diarrhea virus fraction to cattle. Amer J Vet Res 2007, Vol. 68, No. 12: 1417-1422.
Ovarian follicular dynamics in cattle
The study of follicular dynamics began in the mid-20th century, but progress has been particularly rapid in the last two decades through the use of tools that have enabled serial, non-invasive examination. A brief overview of early oogenesis and folliculogenesis is provided as a backdrop to the evolution of our understanding of follicular dynamics during the bovine estrous cycle. Studies to date support the concept that the pair of ovaries acts as a single unit and influences follicular development primarily via systemic endocrine routes involving ovarian and uterine products, the gonadotropins, and their receptors. Dominant and subordinate follicles pass through growing, static and regressing phases that have distinct morphologic and biochemical characteristics; these changes are the basis of efforts focused on diagnosing and manipulating follicular status. An update of research progress highlights recent findings on the repeatability (predictability) within individuals of follicle recruitment and wave pattern (two- versus three-wave cycles), the relationship between oocyte competence and follicular status, and the dynamics of small follicles. Recent studies documented that wave emergence and follicular dominance are apparent earlier than previously reported, and on the basis of periodic endogenous FSH surges and the presence of FSH receptors, the hypothesis that follicles become progressively entrained to waves from the earliest stages of development is introduced. Lastly, recent studies comparing old cows and their young daughters provide a new understanding of the effects of aging on gonadotropins and ovarian steroids, follicular dynamics, ovarian response to synchronization, superstimulation, and oocyte competence.
G.P. Adams, R. Jaiswal, J. Singh, P. Malhi Progress in understanding ovarian follicular dynamics in cattle. Theriogenology Volume 69, Issue 1, Pages 72-80 (January 2008)
Effects of pre-haul management and transport duration on beef calf performance and welfare
Behavioural and physiological indicators of stress as well as growth performance, and morbidity rates were assessed in 174 steer calves (220 ± 37 kg) for 30 days after transport from ranch-to-feedlot. The calves were conditioned (C) or not (NC), and subjected to short- (2.7 h, S) or long-hauling duration (15 h, L), yielding treatments CS, CL, NCS and NCL. Upon arrival at the feedlot, calves were randomly assigned to 16 pens (four pens per treatment, one of which was equipped with a radio frequency identification system for continual monitoring of individual bunk attendance (15 calves)). As part of the NC treatment calves were also exposed to a short (2 h) transport 24 h after their initial arrival to the feedlot. All calves were fed a barley silage/barley grain-based starter ration and weighed every 7 days. Cortisol concentrations were higher in NC compared to C calves regardless of transport distance (P < 0.05). NC calves also had higher pre- and off-loading cortisol concentrations than C calves. In transit, CS steers had the lowest heart rate (HR, 67.8 bpm ±0.61; P < 0.0001). HR was highest (P < 0.05) during the first 15 min of the journey for all calves and gradually declined until 121–161 min into the trip. NC calves spent more time at the feed bunk (222.9 min day−1 versus 128.6 min day−1) in the first 2 days in the feedlot. CL calves were observed more frequently at the water than NCL calves (P < 0.05). An interaction was observed for shrinkage (P < 0.001) and ADG (P < 0.01). Shrinkage was greater in CL than in NCL steers (23.6 kg versus 14.6 kg), and in NCL than in either CS (7.8 kg) or NCS (9.2 kg) steers. The lowest (P < 0.005) ADG was recorded for CL and NCS calves (0.8 and 0.9 kg, respectively), although their DM intake (6.0 and 6.8 kg day−1) was similar (P > 0.05) to calves in the other treatment groups. Morbidity rate was 5.17% with no treatment effect. Conditioning calves prior to transport allowed calves to better tolerate the stressors of transport and handling.
Schwartzkopf-Gensweina, K.S. , M.E. Booth-McLeana, M.A. Shaha, T. Entza, S.J. Bachb, G.J. Mearsa, A.L. Schaeferc, et al. Effects of pre-haul management and transport duration on beef calf performance and welfare. Applied Animal Behaviour Science. Volume 108, Issues 1-2, 10 December 2007, Pages 12-30
Fall-calving cow-calf pairs strip-grazing tall fescue
In a 2-yr study, we evaluated the impact of different forage allocations on the performance of lactating beef cows and their calves grazing stockpiled tall fescue. Allocations of stockpiled tall fescue at 2.25, 3.00, 3.75, and 4.50% of cow-calf pair BW/d were set as experimental treatments. Conventional hay-feeding was also evaluated as a comparison to grazing stockpiled tall fescue. The experiment had a randomized complete block design with 3 replications and was divided into 3 phases each year. From early December to late February (Phase 1) of each year, cows and calves grazed stockpiled tall fescue or were fed hay in the treatments described above. Immediately following Phase 1, cows and calves were commingled and managed as a single group until weaning in April (Phase 2) so residual effects could be documented. Residual effects on cows were measured after calves were weaned in April until mid-July (Phase 3). During Phase 1 of both years, apparent DMI of cow-calf pairs allocated stockpiled tall fescue at 4.50% of BW/d was 31% greater (P < 0.01) than those allocated 2.25% of BW/d. As allocation of stockpiled tall fescue increased from 2.25% to 4.50% of cow-calf BW/d, pasture utilization fell (P < 0.01) from 84 ± 7% to 59 ± 7%. During Phase 1 of both years, cow BW losses increased linearly (P < 0.02) as forage allocations decreased, although the losses in yr 1 were almost double (P < 0.01) those in yr 2. During Phases 2 and 3, few differences were noted across treatment groups, such that by the end of Phase 3, cow BW in all treatments did not differ either year (P > 0.40). Calf ADG in Phase 1 increased linearly (P < 0.01) with forage allocation (y = 0.063x + 0.513; R2 = 0.91). However, calf gain/ha decreased linearly (P < 0.01) as stockpiled tall fescue allocations increased (y = -26.5x + 212; R2 = 0.97) such that gain/ha for cow-calf pairs allocated stockpiled tall fescue at 4.50% BW/d was nearly 40% less (P < 0.01) than for those allocated 2.25% of BW/d. Allocating cow-calf pairs stockpiled tall fescue at 2.25% of BW/d likely optimizes use, because cow body condition is easily regained in the subsequent spring and summer months, less forage is used during winter and calf gain/ha is maximized.
Curtis, L.E., R. L. Kallenbach, C. A. Roberts. Allocating forage to fall-calving cow-calf pairs strip-grazing stockpiled tall fescue. Published online first on December 11, 2007. J. Anim Sci. 1990. 0:jas.2007-0525v1. doi:10.2527/jas.2007-0525
AVMA Offers Online Salary Calculator
The American Veterinary Medical Association offers a free veterinary salary calculator designed to help veterinarians benchmark their annual incomes against similarly employed colleagues. To access: go to the Member Resources section of the AVMA web site (www.avma.org) and click on the Jobs bar. Once logged on, veterinarians can enter a variety of search criteria, including employment type, the species that they work with, whether they are owners or associates, and how many years of experience they have. Along with median salaries, the calculator lists salaries for most categories at the 25th, 75th, and 90th percentile. All information contained in the calculator is drawn from the AVMA Report on Veterinary Compensation. Currently, the calculator lists salary figures from 2005. Once the AVMA completes the survey in 2008 to cover the 2007 salary figures, the data will be updated. All salaries are based on full-time employment.
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